Scaffold-jack.



No. 643,845; Patented Feb. 20, I900. n. A. KUHN.

SGAFFOLD JACK.

(Application filed .mjes, 1899.)

(N0 Model.)

w: mums PETERS on. PHOTO-LUNG" WASHINGTON, q. c.

UNITED STATES PATENT OFFICE.

HARRY A. KIIHN, OF GLEN MILLS, PENNSYLVANIA.

SCAFFOLD-JACK.

SPECIFICATION forming part of Letters Patent No. 643,845, dated February 20, 1900.

Application filed July 28,1899. serial No. 725,389. No model.

5 Pennsylvania, have invented a certain new and useful Improvement in Scaffold-Jacks, of which the following is a specification.

My invention relates to a new and useful improvement in scaffold-jacks, and has for I one of its objects to provide a simple and effective device of this description which may be adjusted for any angle of roof and when so adjusted maybe used in pairs, each balancing and holding the other in place, and thus providing for the support of suitable scaffoldingboards, whereby persons may be enabled to work upon a roof with perfect safety.

A further object of my invention is to provide for the adjusting of the scafiold-jacks upon the roof so as to raise or lower them, and

thus increase the range of work which may be accomplished upon the roof.

With these ends in view this invention consists in the details of construction and combination of elements hereinafter set forth and then specifically designated by the claims.

In order that those skilled in the art to which this invention appertains may understand how to make and use the same, the con- 0 struction and operation will now be described in detail, referring to the accompanying drawings, forming apart of this specification, in which Figure 1 represents a pair of scaffold-jacks 3 5 made in accordance with myimprovement in position upon a roof, the outline of the latter being in dotted lines; Fig. 2, a perspective of my improved scaffold-jack adjusted for use, and Fig. 3 a section ofthe jack when folded o for storage or transportation.

In carrying out my invention as here embodied, A represents the base or main bar of the jack, which is adjusted to rest against the roof when in use, and this bar has a series of 5 holes B formed therein, by means of which the links 0 are adjustably pivoted to the bar by a suitable pin passing through the ends thereof and through one of these holes. This pin may be in the form of a bolt with a nut upon the opposite end thereof or any other suitable arrangement adapted for the purpose.

D is the support, which is pivoted to the 0pposite ends of the links 0 by a corresponding pin or bolt E. This, as is obvious, will give the support a free swinging movement for the purpose hereinafter set forth.

The bar A also has formed therein a series of holes F, by which the links Gare adjustably pivoted thereto, and the opposite ends of these links are pivoted to the stay H. The upper end of the stay has pivoted thereto at I the links J, and these in turn are pivoted at K to the support D, by which arrangement the support may be adjusted, as shown in Figs. 1 and 2, the stay serving to hold it in a horizontal position.

A longitudinal recess or guideway L is formed in the upper side of the bar A and has fitted therein the sliding bar M, which latter terminates in a hook N for the purpose of holding the jack in position. A lug O'is formed upon the inner end of the sliding bar and is adapted to engage any of the holes P in the bottom of the recess L. This arrange ment permits the adjustment of the sliding bar within the recess, so as to vary the loca tion of the jack relative to the hook N.

In practice a pair of jacks are hooked together, as shown in Fig. 1, so that the barA of each shall rest against the roof, and thus balance each other. The supports D are then brought to a horizontal position and the stays I-I so adjusted as to hold them in this position, after which any suitable scaffolding may be placed upon the supports.

In adjusting the bar M the lug O is disengaged from one of the holes B and moved in engagement with another hole of the same series, which may be accomplished by swinging the inner end of the support D out of contact with the bar A and after the adj ustment has taken place moving this end back into contact with the bar A, and consequently with the bar M, thus holding the latter in this adjustment.

When my improved jack is not in use, it maybe readily folded in the position shown in Fig. 3 by turning the stays downward against the bar A, which will also carry the support D downward against the stay, and the bar M may be slid inward to the full extent of the recess, thus shortening the jack and foldin git into a comparativelysmall compass,

making it convenient for shipping or storage. The bar A, support D, and stay H are preferably made of wood, while the links C and G and the bar M are preferably of metal, and, if found necessary, the holes P may have metal bushings Q set therein to protect them against wear.

The cost of manufacturing a jack in accordance with my improvement is small, while its utility is great, as it serves the purpose of supporting a scaffold upon a roof of any angle and may be quickly and readily adjusted to suit Various angles.

Having thus fully described my invention, what I claim as new and useful is- 1 A jack for supporting scaifolds upon roofs of various angles, consisting of a barA having a longitudinal recess formed therein a slide-bar fitted and guided within said recess, a lug projecting downward from the slide-bar and adapted to engage suitable holes formed in the bottom of said recess, a hook formed upon the outer end of the slide-bar whereby it may be engaged with a similar hook of a similar jack in securing both jacks upon the roof, a support, links pivoted to the inner end of the support, said links in turn being adjustably pivoted to the bar A, a stay, links pivoting the stay to the support, and links adjustably pivoting the stay to the bar A, as and for the purpose set forth.

2. The herein-described combination of a bar A having a longitudinal recess L formed therein, a slide-bar fitted within said recess, a lug formed upon the inner end of the bar, bushings set in the bottom of the recess having holes therein for the reception of the lug, a hook formed upon the outer end of the slide-bar, a support adjustably connected to the bar A by two links, a stay, two links pivoting the stay to the support, and two links adjustably pivoting the lower end of the stay to the bar A, as and for the purpose set forth.

In testimony whereof I have hereunto affixed my signature in the presence of two subscribing witnesses.

HARRY A. KUIlN.

Witnesses:

ROBERT TWIGGS, GUnRNsnY A. IlALLownLL. 

